Roughing in Bathroom in Basement Early 1900s vintage house

Hi everyone my name is Eric. First time posting here although I have been on the site many times reading. I live in Minnesota.

Anyways, I'm currently working on roughing in for a 3 piece bath in the basement. The house was built in 1916 I believe. It has extra heavy cast iron drain pipes currently. I'm looking at replacing a 6' or so chunk of the cast iron with PVC and using No hub couplers to attach the PVC to the cast iron. I believe I will use Mission P400 specialty band seal clamps to go from the 4" Xh cI to the 4" PVC replacement sections. From there, I plan on using various sized wye fittings to split off for my shower, toilet and vanity as well as to hook up to the kitchen sink drain line that connects into the section I'll be replacing. 2" no hub couplers to attach the kitchen cast iron line and the laundry cast iron line. I attached a diagram of my plan and I would appreciate any comments or concerns with my plan. I believe I wont need to add any vents as the vanity run and shower run will be under 5" from the main line and will be 2". Is this correct? The toilet will also be well under 6' from the main line. Thanks, Eric

Re vents: what does the distance to the "main line" have to do with anything? I kinda doubt that big vertical cast iron pipe is a vent. If there are no
existing vents down there, you'll need to put some in.

Good chance I'm interpreting wrong on the not needing vents but here what I was referencing. My interpretation of this was that they would all be direct vented by the main stack as they are closer than the max distance for each size vent. 2" for the shower and vanity, 3" for the toilet so within 5' for 2" and 6' on the 3" for the toilet.

You cannot use a "waste line" from another bathroom for a vent, and the way you have drawn it, just about everything is "illegal" for one reason or another. You are out of your "comfort zone" and may have exceeded your "level of incompetence".

You cannot use a "waste line" from another bathroom for a vent, and the way you have drawn it, just about everything is "illegal" for one reason or another. You are out of your "comfort zone" and may have exceeded your "level of incompetence".

Jadnashua - Thanks. Wasn't sure on the wet venting between floors. Appreciate it. The reason all I've done is digging/ breaking concrete is I know I'm not ready to start cutting the pipes and reworking them. So on the diagram I previously posted. 1) All traps need vented 2) I read somewhere else that there is a max number of times you can connect into the main line. What is that number? 3) I'm still working it, but if I were to route the laundry drain and shower line into the toilet drain with a vent right before the shower drain would that that would cover me for venting on the shower correct? Can I wet vent the toilet that way at all? The laundry drain is presently vented and I would keep that vent in place so it would continue to be vented but rather than connect directly to the main with it it would route into the 3" toilet drain. Also just a note. I pulled a permit, it will be 100% inspected. This is a learning experience but Id rather get a solid plan before I cut any pipes/ have the inspector out.

Ok so I'm just ignoring the kitchen and vanity line to focus on figuring out the shower/toilet/ laundry drain lines. In the diagram, the yellow lines are vents, vented straight up. Assuming that the two vents were to connect and go through the roof would these be working locations for them or no?

The number of fixture units draining into the main is what determines its size, not the quantity of taps into it. There are some minimums, like 3" on a toilet, and often, 2" for anything (or above) underneath a slab, IOW, nothing smaller than 2" under a slab in most places. Then, there's a maximum number of degrees change of direction there can be before you need to install a cleanout. Depending on what's being vented and the size of the pipe, determines the maximum length of the trap arm. Your vent always needs to come off the trap arm before the drain turns down.

You can combine vents on the same floor if done at least 6" above the flood plane of the highest fixture, or 42" above the floor, whichever is higher. The same number applies if you tap into it on a floor above if you don't want to run it all the way to the roof. But again, the size of the pipe is based on the number of fixture units you are venting (or draining).

The toilet's vent is okay, but the other one is obscuring the connections behind it so we cannot tell if that would be correct or not. Regardless of what we tell you, the city will make the final decision when you apply for the building permit.

The toilet's vent is okay, but the other one is obscuring the connections behind it so we cannot tell if that would be correct or not. Regardless of what we tell you, the city will make the final decision when you apply for the building permit.

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The city didnt require any sort of a sketch in the plumbing permit application. All they required for my building application was the layout of where the toilet, shower and vanity would be, but didn't require anything about the drain lines which I dont really get why not...

The shower vent is a bit trick to see. Basically, I have it laid out in the center between the drain line that runs from the laundry before the shower (uphill of the shower). If that makes sense. The shower will be a 36x36 so vent would be able to run up through the laundry room.